Stay Cool with a Mister System

Posted: February 1, 2012

Create an oasis in your cockpit when the temperature soars.

By: Nick Felix

As I was walking around the Miami Boat Show, sweating profusely from the 80-plus-degree heat (I’m from the Northeast), I took another step and suddenly felt cooler. Then I saw the reason: I was at the Mist-er-Comfort booth and was enveloped in a cloud of fine mist that seemed to cool the air dramatically. The instant relief I felt convinced me this would be the next DIY project on my 2004 Wellcraft Coastal 270. I spoke to Bill Ford, the company owner, and I learned that they offered a Bimini kit that attaches to the outside of the frame, a complete misting system including stainless steel heads and a high-pressure pump, or an a-la-carte system for a custom install.

I opted for the latter, ordering two stainless steel misting heads with UV grommets, 40 feet of ¼-inch UV-resistant polyethylene tubing, a ¼-inch misting tee union and elbow, and an electric single-zone controller with an auto-drain valve (ADV). This last piece is an important aspect of the system, because when the pump is shut off, it seals to allow pressurization of the misting heads and then automatically drains it into the bilge, which prevents a buildup of calcium that could cause blockage. The ADV also prevents the misting heads from dripping when the system is turned off. I decided to use my existing onboard freshwater holding tank and Shurflo extreme 50 psi water pump. The total cost was around $200.

Install Time

Here are the tools you will need: straight-edge knife, cordless drill, drill bits, fish tape, wire strippers, crimpers, appropriate gauge butt connectors, spade plugs, soldering gun and heat gun.

Additional parts include a marine on/off switch, marine-grade wire, a wire loom, additional grommets for wire and tubing runs to prevent chafing, zip ties and heat-shrink tubing. If you are using your existing pump, you will also need a metric or standard marine tee, based on your boat’s water system, with a ¼-inch output for the tubing.

Step 1: Shut off power to the circuit breaker for 12v power and the existing freshwater pump, if applicable.

Step 2: If you are using an existing pump, install a tee with a ¼-inch output to the pressure side of the cold-water supply line. If you’re installing a stand-alone pump, mount it as close as possible to your freshwater tank. If you don’t have a tank, there are plenty of aftermarket solutions, such as the 7-gallon Aqua-Tainer tanks at West Marine for $22.

Step 3: Install the zone controller box with ADV, or stand-alone ADV, as close as possible to the pump. Keep in mind that the ADV will activate when the system is shut off and needs to drain into the bilge or an area where the water can be removed.

Step 4: Run wire from the zone control box or stand-alone pump to a 12v source, then to the on/off switch. Protect all wiring with a wire loom and grommets.

Step 5: Terminate the wire at the switch, the 12v source, and the zone control box or stand-alone pump using butt connectors, ring terminals, or spade plugs and heat-shrink tubing. For a better connection, solder the termination points when possible.

Step 6: Pick a location for the misting heads, keeping in mind that hardtop installs require you to be able to reach the rear of each misting head to install them. Misting head locations should be a minimum of 2 feet apart for maximum effect and should not be placed directly over any passenger seat, since water can accumulate. For 2012, swiveling heads are available, which I am considering installing.

Step 7: Allow the tubing to sit out in the sun to expand and soften, which will make routing the tubing easier. Run ¼-inch tubing from the zone control box or stand-alone pump to the location of the first misting head. Use a straight-edge knife to cut the tubing. Drill a 3/8-inch hole at the mounting location, and insert a rubber grommet into the hole. Insert the misting head into the grommet, and then attach the tee to the mister from the inside or back. Use additional grommets to protect both wire and tubing runs. Snugly secure all wiring and tubing with zip ties, taking care not to mash the tubing. If you have more than one misting head, repeat this step.

Step 8: Install the main line of tubing into the compression fitting at the stand-alone pump. If an existing pump was used with a zone control box, install the main line of tubing to the ADV. Run a length of tubing from the second input on the zone control box to the existing pump.

Step 9: Remove the misting heads by unscrewing them from their base, preventing debris that may be in the line from clogging the heads. Place a bucket under each head location to catch falling water for the initial test.

Step 10: Turn on the circuit breakers and cycle the system on. Water should flow from each head location. Check the system for any leaks, and correct as necessary. Cycle the system off while viewing the ADV for proper operation. Then reinstall the misting heads, and enjoy this poor man’s cockpit air conditioning.

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